• Pablo Escovedo Helayel, André Roberto Bussman, Diogo Brüggemann da Conceição, and Getúlio Rodrigues de Oliveira Filho.
• Núcleo de Ensino e Pesquisa em Anestesia Regional do CET/SBA Integrado de Anestesiologia da Secretaria de Estado da Saúde de Santa Catarina do Hospital Governador Celso Ramos, Florianópolis, SC. pehelayel@gmail.com
• Rev Bras Anestesiol. 2008 Jul 1;58(4):323-9.

Background And ObjectivesLocal anesthetics (LA) are safe drugs when the proper dose and localization are used. The rate of absorption of the local anesthetic depends on its mass and blood flow at the site of the injection. The objective of this study was to analyze the plasma concentration of 50% enantiomeric excess (S75R25) 0.5% bupivacaine combined with 1:200,000 epinephrine in the parasacral (PS) and infragluteal (IG) sciatic nerve block (SNB).MethodsTwenty-eight patients scheduled for ankle and foot surgeries were randomly divided into two groups in this prospective study. In Group 1, SNB was performed with IG neurostimulation, while in Group 2 the PS method was used. Both groups received 30 mL of 0.5% bupivacaine (S75/R25) with 1:200,000 epinephrine. Arterial blood samples, 5 mL, were drawn at 0, 15, 30, 60, and 90 minutes after the administration of the LA. High-performance liquid chromatography was used to analyze the serum concentrations. Demographic data of both groups were compared using the Student t test for independent samples and Fisher's Exact test. Bifactorial Analysis of Variance for repeated samples was used for the data concerning the plasma concentrations.ResultsGroups 1 and 2 showed no significant demographic differences. The maximal concentration (Cmax) in Group 1 (308 +/- 91 ng.mL(-1)) was obtained in samples number 5 (90 minutes), while in Group 2 (425 +/- 280 ng.mL(-1)) it was obtained in samples number 2 (15 minutes). Cases of systemic toxicity were not observed.ConclusionsCmax of 0.5 % bupivacaine (S75/R25) with 1:200,000 in the parasacral approach was higher when compared with the infragluteal SNB.

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